Thanks for the reply Enduriel!

Yes, i have set the polygon flag, with no luck. The ball is working just fine if i drop in a big room with 4 walls. I have tried with just quad's in mesh, tri's in mesh and with a "shell around the mesh to give it thickness, so far no luck. This is very wierd. Could you or anyone else in that case look at my project setup? I would appreciate it alot. Btw, great software, lots of opportunity!